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340b39ea31
The descendants tracker is a generic tracker that you can use anywhere. In particular, outside Rails applications. Should provide API to clear only a subset of classes, but in my view should know nothing about autoloading. That is a concern of client code.
98 lines
3.1 KiB
Ruby
98 lines
3.1 KiB
Ruby
# frozen_string_literal: true
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require_relative "abstract_unit"
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require "set"
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require "active_support/descendants_tracker"
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class DescendantsTrackerTest < ActiveSupport::TestCase
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setup do
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@original_state = ActiveSupport::DescendantsTracker.class_eval("@@direct_descendants").dup
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@original_state.each { |k, v| @original_state[k] = v.dup }
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ActiveSupport::DescendantsTracker.clear
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eval <<~RUBY
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class Parent
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extend ActiveSupport::DescendantsTracker
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end
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class Child1 < Parent
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end
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class Child2 < Parent
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end
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class Grandchild1 < Child1
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end
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class Grandchild2 < Child1
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end
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RUBY
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end
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teardown do
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ActiveSupport::DescendantsTracker.class_eval("@@direct_descendants").replace(@original_state)
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%i(Parent Child1 Child2 Grandchild1 Grandchild2).each do |name|
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DescendantsTrackerTest.send(:remove_const, name)
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end
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end
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test ".descendants" do
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assert_equal_sets [Child1, Grandchild1, Grandchild2, Child2], Parent.descendants
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assert_equal_sets [Grandchild1, Grandchild2], Child1.descendants
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assert_equal_sets [], Child2.descendants
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end
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test ".descendants with garbage collected classes" do
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# The Ruby GC (and most other GCs for that matter) are not fully precise.
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# When GC is run, the whole stack is scanned to mark any object reference
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# in registers. But some of these references might simply be leftovers from
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# previous method calls waiting to be overridden, and there's no definite
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# way to clear them. By executing this code in a distinct thread, we ensure
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# that such references are on a stack that will be entirely garbage
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# collected, effectively working around the problem.
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Thread.new do
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child_klass = Class.new(Parent)
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assert_equal_sets [Child1, Grandchild1, Grandchild2, Child2, child_klass], Parent.descendants
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end.join
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# Calling `GC.start` 4 times should trigger a full GC run
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4.times do
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GC.start
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end
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assert_equal_sets [Child1, Grandchild1, Grandchild2, Child2], Parent.descendants
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end
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test ".direct_descendants" do
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assert_equal_sets [Child1, Child2], Parent.direct_descendants
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assert_equal_sets [Grandchild1, Grandchild2], Child1.direct_descendants
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assert_equal_sets [], Child2.direct_descendants
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end
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test ".subclasses" do
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[Parent, Child1, Child2].each do |klass|
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assert_equal klass.direct_descendants, klass.subclasses
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end
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end
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test ".clear deletes all state" do
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ActiveSupport::DescendantsTracker.clear
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assert_empty ActiveSupport::DescendantsTracker.class_eval("@@direct_descendants")
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end
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test ".clear(only) deletes the given classes only" do
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ActiveSupport::DescendantsTracker.clear(only: Set[Child2, Grandchild1])
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assert_equal_sets [Child1, Grandchild2], Parent.descendants
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assert_equal_sets [Grandchild2], Child1.descendants
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assert_equal_sets [Child1], Parent.direct_descendants
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assert_equal_sets [Grandchild2], Child1.direct_descendants
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end
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private
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def assert_equal_sets(expected, actual)
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assert_equal Set.new(expected), Set.new(actual)
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end
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end
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